Numerical Investigation of Short Blades Effect on the Performance of a Centrifugal Pump

Abstract

Improvement performance of centrifugal pumps is critical to reduce the consumption of electrical energy. One to improve the performance is to break down the circulation near the impeller exit. This can be achieved through the use of shorted blades. Effect of different sizes of shorted blade on pump performance is studied theoretically in this research which, test rig for testing centrifugal pump with standard impeller is constructed. Three impeller configurations with different size shorted blade are installed. The head, flow rate and shaft power are measured at 1500 rotational speed for the standard pump only. Also computational model using “Fluent” under ANSYS is constructed to predict the performance parameters of centrifugal pumps and to analyze the flow field in the impellers’ passages. Standard impeller (A) and three impellers configuration with different shorted blade length of 0.25 (configuration B), 0.2 (configuration C), and 0.15 (configuration D) of the full blade length are analyzed. Computational results show a reduction in flow circulation for all shorted blades impeller comparing to standard impeller. Also static pressure distributions at impeller exit become more uniform for impeller with 0.25, 0.2, and 0.15 shorted blades. The present work proves that the length of short blades have different effects for all pump cases. The best performance in this study occurred when shorted blades have length 25% from the original blade length. So when the effect of shorted blades is needed to study, each case of centrifugal pump should be investigated separately.